prelim FAQ update: Installation Instructions

[DJ Delorie]

> Good idea.  While I was playing around with setup on a test machine,
> trying different things, I found that Setup would provide C:\ as a
> default root under certain circumstances, generally when the
> previous Setup attempt was aborted (^C).  It looked like registry
> entries were created, but perhaps not populated correctly.  This
> scenario might be confusing to a new user.  Can Setup avoid it
> somehow?  (This was Win98, BTW.)

The mount changes will be the very last thing it does, so that
particular problem shouldn't happen any more.